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Superconductivity Current. Section 54. A simply connected body can have no steady surface current in the absence of an external magnetic field.
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Superconductivity Current Section 54
A simply connected body can have no steady surface current in the absence of an external magnetic field.
In spherical coordinates, DY = 0 has solutions that are powers of r: ra, where a can be positive or negative. If dY/dr is zero at both r = a and r = infinity, the only possible value of a is zero. Then dY/dr = 0 at all r, or Y = constant, giving H = 0. An H-field of this kind cannot exist -> there can be no steady current on a simply connected body.
For a simply-connected body in an external H-field, a magnetic moment M appears
Multiply connected superconductor f is many valued
Zero, since H=B outside and divB = 0.